* Airline has been key player in HNA’s deleveraging efforts (Adds background)

SHANGHAI/BEIJING, May 17 (Reuters) - Hainan Airlines , a carrier affiliated with embattled HNA Group , said a Chinese provincial regulator was its controlling entity but flagged that control of the firm may change hands amid a widespread restructuring of its assets.

HNA, a major aviation-to-financial services group, has been criticised for its opaque structure and has seen some deals unravel due to ownership concerns. After a $50 billion acquisition spree over a two-year period, it is now undertaking a restructuring to raise cash by selling equity and real estate assets amid a government crackdown on debt.

Because of the government crackdown, more details about the group’s ownership structure are now emerging.

Hainan Airlines, China’s fourth-biggest carrier, is widely believed to be controlled by HNA, but on Thursday the carrier told an online investor conference that Hainan’s State-owned Assets Supervision and Administration Commission (SASAC) controls it through SASAC’s stake in Grand China Air Co Ltd.

Trading in Hainan Airlines’ shares has been suspended since January, as have shares in six other HNA-affiliated companies listed on mainland stock markets, as the firms undertake a “major asset restructuring”. The carrier said on Thursday the restructuring may lead to a change of control.

“The company is currently communicating, negotiating and proofing its asset restructuring plan, and there is a possibility that the actual controller of the company could change,” the carrier’s president, Xu Jun, told investors in a chatroom post.

“It will ultimately be determined after the plan is approved by the relevant authority.”

Since the start of 2018, HNA Group has agreed to sell close to $15 billion worth of real estate in Australia, New York and Hong Kong, along with shares in Deutsche Bank AG, and Hilton Worldwide Holdings Inc.

The conglomerate ultimately traces its roots back to Hainan Airlines, which was started by Chen Feng, a former government official who went on to establish HNA Group and now chairs both companies.

The airline’s early investors included George Soros, the billionaire financier who at one point controlled a 25 percent stake in the carrier. He has since sold out.

Hainan Airlines has now become a key player in HNA’s bid to reconfigure its operations. In March, it said it would take over stakes owned by HNA in two local airlines and five other aviation and tourism businesses. ($1 = 6.3647 Chinese yuan renminbi) (Reporting by Brenda Goh in SHANGHAI and Matthew Miller in BEIJING; Additional reporting by Beijing and Shanghai Newsrooms; Editing by Muralikumar Anantharaman)